NCERT 7th Class (CBSE) Science: Fibre to Fabric

Question: Name the domesticated moth whose larva produces silk.

Answer: Silk is obtained from the cocoon of the pupa of mulberry silk moth.

Question: Where does a female silk moth lay eggs?

Answer: Female silk moth lays eggs on mulberry leaves.

Question: In which stage the silk moth spins the silk fibre around itself?

Answer: Caterpillar.

Question: What is cocoon?

Answer: The cocoon is a single continuous thread of about 1.5 km length.

Question: Why are cocoons immersed in boiling water?

Answer: Cocoons are immersed in boiling water to separate cocoon from larva, in this process the silkworm is killed.

Question: Name the sticky fluid secreted by larva (caterpillar) from its salivary glands.

Answer:  The sticky fluid secreted by larva is protein called fibroin.

Question: What is meant by reeling?

Answer: The process of separating the silk filaments from the cocoons is called reeling of the silk.

Question: Which fibre gives the smell of burning hair?

Answer: Wool.

Question: What are burrs?

Answer: The small fluffy fibres in wool are called burrs.

Question: Write any two health hazards faced by workers in sericulture and wool production.

Answer: The two health hazards are:

1. Handling of dead silk worms with bare hands may lead to infection and illness.
2. One of the serious health hazards for workers in the wool production industry is exposure to a type of bacteria called anthrax. It causes a disease called wool sorter’s disease.